The use of volatile anesthetic gases offers considerable advantages over barbiturates for experimental studies requiring prolonged surgery in small laboratory animals. In particular, continuous control of the depth of anesthesia is more readily obtained with fact-acting inhalation gases than with barbiturates. In addition, animals recover quickly once the volatile type anesthetic gas is removed, thereby permitting early observation of the animal's behavior.
At the present time no satisfactory system exists for providing safe delivery of volatile anesthetics to small animals. For example, it is common to use the barrel of a syringe or a funnel-like mask to deliver anesthetic gases to the animal. The problem with such devices is that they permit the anesthetic gas to escape into the surrounding atmosphere. The volatility and toxicity of such gases present a considerable danger to the laboratory personnel working near the anesthetized animal. Moreover, the prior art devices used for this purpose are often applied too tightly to the animal, resulting in pressurization of the animal's lungs which could alter the pulmonary function.
It is therefore an object of the present invention to provide a mask for delivering inhalation gases to small animals which is safe for the animal and safe for personnel in the surrounding area.